Spark ignition system

ABSTRACT

A spark ignition system is designed for a two-stroke or fourstroke cycle internal combustion engine and having first and second cylinders with pistons arriving at the combustion dead center position and the non-combustion dead center position thereof simultaneously. First and second sparkplugs in each cylinder are joined to the corresponding terminals of an ignition distributor energizing one of the sparkplugs in one cylinder at an effective cycle time and simultaneously energizing the corresponding sparkplug in the other cylinder at an ineffective cycle time. Both remaining sparkplugs are similarly energized. The two sparkplugs in any cylinder are fired effectively once each cycle but a few degrees of engine rotation apart.

United States Patent Mathews Feb. 26, 1974 [54] SPARK IGNITION SYSTEM 3,716,991 2/1973 Tatsutomi 123/148 DS [75] Inventor: Clinton S. Mathews, Oakland, Calif.

Primary ExammerLaurence M. Goodridge [73] Assigneez De Laval Turbine California, Inc., Assistant Examiner CO1-t Flint Oakland, Calif- Attorney, Agent, or FirmLothrop & West [22] Filed: May 18, 1972 [211 App]. No.: 254,747 [57] ABSTRACT A spark ignition system is designed for a two-stroke or four-stroke cycle internal combustion engine and hav- [52] 123/148 123/148 123/148 ing first and second cylinders with pistons arriving at Int Cl F02 /0 36 2 55 the combustion dead center position and the nonp combustion dead center position thereof simulta- [58] Field of Search "123/148 148 148 neously. First and second sparkplugs in each cylinder are joined to the corresponding terminals of an ignition distributor energizing one of the sparkplugs in [56] References C'ted one cylinder at an effective cycle time and simulta- UNITED STATES PATENTS neously energizing the corresponding sparkplug in the 846,809 3/1907 Varley et a1. 123/148 C other cylinder at an ineffective cycle time. Both re- 1,599,354 9/1926 Arnold 123/148 C maining sparkplugs are similarly energized. The two ,6 1/1966 Muller i 123/14 D3 sparkplugs in any cylinder are fired effectively once 3,430,617 3/1969 i 123/149 R each cycle but a few degrees of engine rotation apart. 3,554,092 l/l97l Shlbagaki... 123/148 DS 3,669,086 6/1972 Beuk 123/148 E 4 Claims, 2 Drawing Figures l,4 CENTER FIRING ORDER I,3,4,2

SPARK IGNITION SYSTEM in relatively large engines, particularly multicylinder, piston engines operating on the two-stroke or four-stroke cycle with spark ignition and on a generally homogeneous fuel, there may be difficulty with flame propagation, with excessive detonation in the combustion chamber, with fuel economy and with maintaining engine operation should part of the ignition mechanism fail.

it is therefore an object of my invention to provide an ignition arrangement for a spark ignition engine to overcome these difficulties.

Another object of the invention is to provide ignition for a multi-cylinder engine in which each cylinder is given ignition sparks at different times in different locations without undue complication.

Another object of the invention is to provide an improved ignition system for a spark ignition engine.

A further object of the invention is to provide an ad aptation to standard structure utilized with spark ignition engines so that the sparking conditions can substantially be improved.

A still further object of the invention is on general to provide an improved spark ignition system for an internal combustion engine.

Other objects, together with the foregoing, are attained in the embodiment of the invention described in the accompanying description and illustrated in the accompanying drawings, in which:

FIG. 1 is a diagrammatic illustration of an engine and its accompanying ignition system pursuant to the invention; and

FIG. 2 is a diagram showing the timing arrangement of the ignition system pursuant to the invention as provided in connection with the engine of FIG. 1.

In a representative environment there is provided an internal combustion engine 6 including a frame 7 in which a multi-throw crankshaft 8 is situated for rotation. As an example, the engine is considered to be a four-stroke cycle engine and to have four cylinders. The crankshaft 8 is arranged so that all of the crank throws are in a single diametrical plane. The throw 9 for cylinder 1 is in the same attitude as throw 11 for cylinder 4. 180 out of phase with these throws but still in the same plane are the throws 12 for cylinder 2 and 13 for cylinder 3.

in the customary fashion, the various crankshaft throws are connected by intervening connecting rods 15 to a number of pistons 16. Each of the cylinders 1, 2, 3 and 4 is, for example, 12 inches or more in bore and has a stroke of a proportional amount. The cylinders are all supplied with standard induction and exhaust mechanisms, not shown. Each cylinder is particularly provided with one of a group of central sparkplugs 17, 18, 19 and 20. The central sparkplugs ignite the combustible mixture reasonably well but not as well as is the case when additional sparkplugs are utilized. For that reason, each of the cylinders 1, 2, 3 and 4 is also equipped with one of a group of side sparkplugs 22, 23, 2 i and 25.

Appropriate means are afforded for energizing the various sparkplugs in time with the operation of the engine. To that end the engine crankshaft 8 at one end carries a timing pinion 27 in mesh with an ignition distributor pinion 28 of twice the diameter in order to drive a distributor shaft 29 at half the rate of the crankshaft.

The shaft 29 drives a rotor arm 31 of grounded ignition distributor 32. This is substantially standard. A conductor 33 extends between a center point on the rotor 31 and one terminal 34 of a source of electrical energy such as a storage battery 36. The other terminal 3'7 of the battery is joined by a conductor 38 to the frame 7 of the engine. The ignition system is of any usual kind. Reference to sparkplugs also includes combined high tension coils and spark gaps.

At one end the rotor carries an electrical energizing device 41. During its rotation the device sweeps into and out of juxtaposition or registry with an electrical connector or energizing point 42 in the distributor shell 43. This is joined by a conductor 44 to the side sparkplug 22 in cylinder 1 and also to the side sparkplug 25 in cylinder 4.

In a comparable fashion, the distributor shell has an electrical point 45 away from the point 42 and joined by a conductor 46 to the side sparkplug 23 of cylinder 2 as well as to the side sparkplug 24 of cylinder 3. Also included in the circular cylindrical shell 43 is an electrical point 47 spaced from the point 42 in the direction (arrow 48) of rotor rotation something other than or more than one hundred eighty degrees. The point 47 is joined by a conductor 49 to the center sparkplug 17 of cylinder 1 as well as to the center sparkplug 20 of cylinder 4. Similarly, the distributor shell has a point 50 leading through a conductor 51 to the center plug 18 of cylinder 2 as well as to the center plug 19 of cylinder 3.

Particularly in accordance with the invention, the points 47 and 50 are ninety degrees apart. The points 42 and 47 are not diametrically opposite each other, but are a few degrees away from that location, and the points 45 and 50 are not diametrically opposite each other, but are spaced apart a few degrees away from that amount.

To work with these point locations, the standard rotor 31 is provided with a second arm 52 having an electrical energizing terminal 53 thereon. the arm 52 being away from the arm 31 and the electrical terminals ll and 53 being 180 away from or diametrically opposite each other.

Since the preferred firing order of the engine is 1, 3, 4, 2, the firing diagram of FIG. 2 shows the sequence of firing operations with this arrangement. The diagram extends for more than two revolutions of the crankshaft 8, but can be initially considered from the aspect of cylinder 4 with the piston 16 therein adjacent extended or top dead center position, distinguished from the other or bottom dead center position in which the piston is close to the throw of the crankshaft.

As shown in FIG. 1, the rotor arm 31 is in position with the electrical points 41 and 42 facing or registering with each other. when this in true, standard intermediate mechanism of suitable nature, not shown, makes the conductor 44 effective to fire the side sparkplugs 22 and 25 of cylinders 1 and 4. Preferably this firing of both plugs simultaneously takes place slightly before top dead center position of the pistons 16 in cylinders 1 and 41. if it is assumed that cylinder 4 is near completion of its compression stroke after having been charged with combustible mixture, then the firing of the side sparkplug 25 initiates combustion near one side of cylinder 4. Although the side sparkplug 22 in cylinder 1 is simultaneously energized, it produces no effect since the piston 16 in cylinder 1 at this juncture is near completion of its exhaust stroke. The spark occurring in cylinder 1 at this time is mere surplusage and does no harm.

As the rotor arms 31 and 52 continue to rotate in a clockwise direction 48 as seen in FIG. 1, the next event, a few degrees later, is the substantial registry of the electrical members 53 and 47, thus energizing the conductor 49 simultaneously to energize the center plug 17 of cylinder 1 and the center plug of cylinder 4. As shown in the diagram, the resulting spark in cylinder 1 at the center sparkplug is ineffective because this cylinder is at the end of its exhaust stroke and there is nothing to explode. But the simultaneous energization of the center sparkplug 20 of cylinder 4 produces central ignition of the compressed combustible mixture since cylinder 4 is at the end of its compression stroke. That is, the spark in cylinder 1 is useless, but the spark in cylinder 4 augments the ignition.

It may be observed both in the diagram of FIG. 2 and in the layout of the distributor head in H6. 1 the sparks at the side of the cylinders occur slightly before the sparks occur at the center of the cylinders. Preferably the timing differences conform to the rate of flame propagation so that both sparks occur at times so spaced as materially to reduce total flame propagation time and materially to improve the combustion. Preferably the difference in timing in each given engine is such that the flame propagation from both effective sparkplugs in the cylinder provides detonation-free combustion and thorough combustion of the available materials. Stated differently, the spark at the center of cylinder 4 promotes combustion at the center and is followed by a power stroke. The simultaneous spark in the central plug in cylinder 1 is mere surplusage.

As the engine and distributor continue their cycle, as can be observed in FIG. 2, cylinder 2 first has its side plug fired at the same instant that the side plug in cylinder 3 is fired. Cylinder 3 at that time is at the end of its exhaust stroke, so that the spark is ineffective. Cylinder 2 is atthe end of its compression stroke, so the side sparkplug initiates combustion. A few degrees later, simultaneous sparks are produced in cylinder 2 at the center plug and in cylinder 3 at the center plug. The

center spark in cylinder 2 is effective since it occurs toward the end of the compression stroke in that cylinder, but the center spark is ineffective in cylinder 3 since that cylinder is ending its exhaust function. The operations in all four cylinders are shown, and the general description herein with respect to cylinders 1 and 3 also indicates the operation of the remaining pairs of cylinders.

This disclosure is especially concerned with a fourcylinder, four-stroke cycle engine but the present arrangement is equally applicable to two-stroke engines in which effective and ineffective sparks can occur. The number of cylinders is limited only by practical reasons, having been incorporated in engines up to sixteen cylinders having a cylinder bore of about 13 inches and a piston stroke of about 15 inches. The actual fuel economy is improved, detonation is substantially reduced, and if part of one ignition system fails the other serves as a standby to maintain engine operation. The alteration in the standard ignition distributor is relatively small in that it requires merely the utiliza tion of a double rotor construction and slightly different positioning of the usual and of additional electrical points in the distributor shell. The arrangement is such that while the ordinary firing is:

there results a firing order after the instant device has been connected of: 1,4 S 1,4 C 2,3 8- 2,3 C 1,4 Sll,4C-2,3S2,3C.

Thus with very little mechanical change in the normal electrical distributor and with the provision of a dual sparkplug system and appropriate connecting conductors, it is feasible to count on a reduced fuel consumption, a reduced amount of detonation and a system that increases reliability by allowing the continued operation of the engine on but one system should the other one fail.

What is claimed is:

l. A spark ignition system for a reciprocating piston internal combustion engine operating on a multi-stroke cycle and having at least first and second separate cyl inders with separate pistons arriving at dead center position at approximately the same time comprising first and second sparkplugs in each of said cylinders, a rotary ignition distributor, means for driving said distributor from said engine, a first ignition circuit connected to said first sparkplug in said first cylinder and to said first sparkplug in said second cylinder, a second ignition circuit connected to said second sparkplug in said first cylinder and to said second sparkplug in said second cylinder, means including said distributor for energizing said first ignition circuit and simultaneously firing both of said first sparkplugs to initiate combustion in one of said cylinders at one predetermined time in the cycle of said engine, and means including said distributor for energizing said second ignition circuit during said combustion and simultaneously firing both of said second sparkplugs at a later predetermined time in the cycle of said engine.

2. A system as in claim 1 in which said first sparkplugs are farther from the center of their respective cylinders than are said second sparkplugs, and said first circuit is energized earlier in the cycle of said engine than is said second circuit.

3. A spark ignition system for a reciprocating piston engine having at least first and second'separate combustion chambers comprising means for operating said engine to provide events in said first combustion chamber beginning at a predetermined time and in sequence as follows: fuel mixture admission, fuel mixture compression, fuel mixture expansion, fuel mixture exhaust and to provide in said second combustion chamber beginning at a later time and in sequence as follows: fuel mixture admission, fuel mixture compression, fuel mixture expansion, fuel mixture exhaust; first and second sparkplugs in said first combustion chamber; third and fourth sparkplugs in said second combustion chamber; means for firing said first sparkplug toward the end of said compression event in said first combustion chamber to initiate combustion therein and for simultaneously firing said third sparkplug toward the end of said exhaust event in said second combustion chamber; means for firing said second sparkplug in said first combustion chamber during said combustion a few degrees of engine operation after said firing of said first sparkplug and'simultaneously firing said fourth sparkplug;

degrees after firing of said third sparkplug and simultaneously firing said second sparkplug.

4. A system as in claim 3 in which said first and third sparkplugs are remote from the center of said combustion chambers and said second and fourth sparkplugs are close to the center of said combustion chambers 

1. A spark ignition system for a reciprocating piston internal combustion engine operating on a multi-stroke cycle and having at least first and second separate cylinders with separate pistons arriving at dead center position at approximately the same time comprising first and second sparkplugs in each of said cylinders, a rotary ignition distributor, means for driving said distributor from said engine, a first ignition circuit connected to said first sparkplug in said first cylinder and to said first sparkplug in said second cylinder, a second ignition circuit connected to said second sparkplug in said first cylinder and to said second sparkplug in said second cylinder, means including said distributor for energizing said first ignition circuit and simultaneously firing both of said first sparkplugs to initiate combustion in one of said cylinders at one predetermined time in the cycle of said engine, and means including said distributor for energizing said second ignition circuit during said combustion and simultaneously firing both of said second sparkplugs at a later predetermined time in the cycle of said engine.
 2. A system as in claim 1 in which said first sparkplugs are farther from the center of their respective cylinders than are said second sparkplugs, and said first circuit is energized earlier in the cycle of said engine than is said second circuit.
 3. A spark ignition system for a reciprocating piston engine having at least first and second separate combustion chambers comprising means for operating said engine to provide events in said first combustion chamber beginning at a predetermined time and in sequence as follows: fuel mixture admission, fuel mixture compression, fuel mixture expansion, fuel mixture exhaust and to provide in said second combustion chamber beginning at a later time and in sequence as follows: fuel mixture admission, fuel mixture compression, fuel mixture expansion, fuel mixture exhaust; first and second sparkplugs in said first combustion chamber; third and fourth sparkplugs in said second combustion chamber; means for firing said first sparkplug toward the end of said compression event in said first combustion chamber to initiate combustion therein and for simultaneously firing said third sparkplug toward the end of said exhaust event in said second combustion chamber; means for firing said second sparkplug in said first combustion chamber during said combustion a few degrees of engine operation after said firing of said first sparkplug and simultaneously firing said fourth sparkplug; means for firing said third sparkplug toward the end of said compression event in said second combustion chamber to initiate combustion therein and for simultaneously firing said first sparkplug toward the end of said exhaust event in said first combustion chamber; and means for firing said fourth sparkplug during said combustion in said second combustion chamber a few degrees after firing of said third sparkplug and simultaneously firing said second sparkplug.
 4. A system as in claim 3 in which said first and third sparkplugs are remote from the center of said combustion chambers and said second and fourth sparkplugs are close to the center of said combustion chambers. 